Components used in stationary turbomachines, such components are for example compressor blades or vanes, gas turbines blades or vanes or heat shielding segments etc. are made of high alloyed (10% to 18% chromium) steels, nickel base alloys or cobalt base alloys. Those materials are the substrate materials of the turbomachine components.
In the prior art there are commercially available coating systems, for example SermeTel® 6000, which are used to protect compressor blades of industrial gas turbines. However, these systems have, due to Aluminum particles as sacrificial coating, good corrosion resistance but poor erosion resistance.
Document U.S. Pat. No. 6,159,618 relates to a multi-layer material that comprises a substrate made of aluminum, magnesium or their alloys, having possibly been subjected to a surface treatment, for example anodizing. The described technical solution is related to aircraft engines, for example propellers, rotors etc., which use light-weight materials. The substrate is being provided with a coating comprising a tungsten based deposit and an underlayer inserted between said substrate and said deposit of a material having mechanical and thermo-mechanical properties intermediate to those of said substrate and said deposit. Said tungsten based deposit can include at least one layer made of a material chosen for example from among tungsten, the carbides, silicides and nitrides of tungsten, tungsten alloys and their mixtures and solid solutions of nitrogen and of carbon in tungsten. The tungsten based deposit can comprise a single one of these layers or a stack of several of these layers. The underlayer can be composed of a single layer of a material chosen from among the materials quoted above such as chromium, molybdenum, niobium, titanium, zirconium, their nitrides and carbides, solid solutions of carbon and nitrogen in said metals, steels, aluminum-tungsten with a composition gradient and aluminum oxide.
Document JP 58020996 A discloses a corrosion-resisting and acid-resisting coating layer, for instance, of a flake resin obtained by admixing scale like glass flake to a resin of unsaturated polyester or vinyl ester being applied over the entire surface of a blade which is made of an ordinary material such as SS41. After drying and curing the coating layer, its surface is roughed by use of a hand grinder or emery paper. Then, a coating layer of a room temperature curing, erosion resisting material such as Fluor rubber is applied to the roughened surface of the coating layer, so that the blade is imparted with both of corrosion-resisting and erosion-resisting properties over the entire surface thereof. According to the above arrangement, efficiency of the blade manufacturing operation can be improved by reducing the thickness of both of the coating layers.
Document U.S. Pat. No. 5,740,515 discloses an article of manufacture which is subject to erosive and corrosive attack in a high-temperature environment, and which is formed of a substrate of nickel or cobalt-based superalloy, and a protective silicide coating disposed on the substrate. A thermal barrier layer of ceramic may be disposed between the superalloy and the silicide layer, and a MCrAlY layer may be disposed between the ceramic and the superalloy substrate. The silicide coating is preferably MoSi2.
Document US 2008/0317601 A discloses a turbomachine blade, which includes a blade body and a corrosion and erosion protective multilayered coating bonded thereto, the multilayered coating including an erosion resistant first layer at least covering a corrosion and erosion critical area of the blade body, and a sacrificial second layer provided over the first layer at least covering the first layer, preferably covering the blade totally. A method of manufacturing such a turbomachine blade includes the steps of providing a blade and depositing the erosion resistant first layer on the blade body so as to cover at least the corrosion and erosion critical area, followed by depositing the sacrificial second layer over the first layer at least covering the first layer.
Document US 2011/0165433 A teaches a process for providing a protective coating to a metal surface by applying a nickel or tantalum plate layer to the surface and dispersing particles of a hard material such as diamond, alumina, vanadium nitride, tantalum carbide and/or tungsten carbide within the nickel or tantalum plate layer as the plating is occurring.
There is still a need for a turbomachine component made of high alloyed steels, titanium alloys, nickel base alloys or cobalt bases alloys as a substrate, which is used in stationary turbomachines, and comprising a corrosion resistant coating, which coating can be used as base coat for an erosion resistant coating to simplify the protection of such components of stationary turbomachines.